package com.scs.application.core.mvc.condition;

import org.springframework.web.servlet.mvc.condition.RequestCondition;

import javax.servlet.http.HttpServletRequest;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @Description: 版本号匹配筛选器
 */
public class ApiVersionCondition implements RequestCondition<ApiVersionCondition> {
    /**
     * 路径中版本的正则表达式匹配， 这里用 /v1.0的形式
     */
    private static final Pattern VERSION_PREFIX_PATTERN = Pattern.compile("^/v(\\d)/.*?$");
    private int apiVersion;

    public ApiVersionCondition(int apiVersion) {
        this.apiVersion = apiVersion;
    }

    @Override
    public ApiVersionCondition combine(ApiVersionCondition other) {
        // 采用最后定义优先原则，则方法上的定义覆盖类上面的定义
        return new ApiVersionCondition(other.getApiVersion());
    }

    @Override
    public ApiVersionCondition getMatchingCondition(HttpServletRequest request) {

        Matcher m = VERSION_PREFIX_PATTERN.matcher(request.getRequestURI());
        if (m.find()) {
            Integer version = Integer.valueOf(m.group(1));
            // 如果请求的版本号大于配置版本号， 则满足
            if (version >= this.apiVersion) {
                return this;
            }
        }
        return null;
    }

    @Override
    public int compareTo(ApiVersionCondition other, HttpServletRequest request) {
        // 优先匹配最新的版本号
        return Integer.compare(other.getApiVersion(), this.apiVersion);
    }

    public int getApiVersion() {
        return apiVersion;
    }

}
